Desertification phenomenon Lecture 3 Desertification phenomenon

“Desertification is one of the world’s most alarming processes of environmental degradation” “For most drylands dwellers, life is hard and the future often precarious. They live on the ecological, economic and social margins. It is essential that we do not neglect them or the fragile habitats on which they depend,” Kofi Annan _Former UN secretary general International Year of Desert and Desertification, 2006

Dryland fact points Drylands cover more than 40 per cent of the earth's surface. There are nearly 2 billion drylands dwellers. It affects one third of the earth’s surface and over a billion people. More than 110 countries, particularly in Africa, Asia and Latin America, have drylands that are potentially threatened by desertification. 24 billion tons of fertile soil disappear annually. Each year, desertification and drought cause an estimated $42 billion in lost agricultural production. The middle east hold up to 93% of drylands, while two thirds of the African continent is desert or drylands.

Major deserts of the world Area (km2) location Desert name 13,829,430 Antarctica Antarctic desert 13,726,937 Alaska, Canada, Finland, Greenland(Denmark), Iceland, Norway, Russia and Sweden Arctic 900,000 Algeria, Chad, Egypt, Eritrea, Libya, Mali, Mauritania, Morocco, Niger, Sudan, Tunisia and Western Sahara Sahara 2,330,000 Iraq, Jordan, Kuwait, Oman, Qatar, Saudi Arabia, United Arab Emirates and Yemen Arabian Desert 1,300,000 China and Mongolia Gobi Desert Angola, Botswana, Namibia and South Africa Kalahari Desert 670,000 Argentina and Chile Patagonian Desert 647,000 Australia Great Victoria Desert 520,000 Iraq, Jordan and Syria Syrian Desert

Desert of Saudi Arabia Deserts of Saudi Arabia are originated from the vast northern desert (border of Syria, Iraq and Jordon) Desert are formed as a result of sand dune movement from the northern and north western side of the peninsula especially in summer. Major deserts are Alnofod, Aldahna, Alsaman and The empty quarter.

Desert of Saudi Arabia

Desertification is simply the processes that results in the degradation of the environment and ecosystems (i.e. low ground water levels, Stalinization of top soil and water, low vegetation cover, soil erosion) All these process would increase the total area of the desert replacing vegetation. The Desertification term was first used by the French botanist Aubreville in 1949, to refer to the transformation of productive agricultural land into a desert-like condition.

Desertification term has since been widely used as human been started to sense the scope of the problem, desert lands were increasing as human population along with food demands increase. This of course was much more noticed and significant in arid and semi arid lands where food and water resources scarce. (thus any minimal changes in the fragile ecosystem can result in a disaster). For example, in 1963, the eastern coast of Africa (the southern border of the Sahara desert) containing Lake Chand has suffered continuous drought for almost 4 decades.

This prolong drought has decreased the size of the lake to 1/3 its original size and resulted in the drying of the whole land extending to the borders of the Sahara desert in the north.

1973 1963 1997 1987 Lake Chad is located on the border of 4 African countries : Chad, Nigeria, Niger, Cameroon was one day the sixth largest lake in the world and as a result of successive droughts since 1963, has become an area of far less than 1/10 (ten) original size.

Desertification definition: “a process by which natural or artificial degradation of land resources occur under the effect of extreme drought in climate and soil”. UNCED, 1992

What is the relationship between drought and desertification? Kassas (1995): Desertification: degradation and corrosion of land resources due to natural and human factors. Drought: the retention of rain resulting in land aridity.

Causes and effect of desertification Human causes: overgrazing, Farming of Average Land, Destruction of Plants in Dry Regions, Incorrect Irrigation, increased population, poverty, policy and instrumental shortcomings. Natural causes: Climate change (drought/rain retention, increased wind/ high evapotranspiration)

Human causes of desertification Overgrazing: was not as large of a problem long ago because animals would move in response to rainfall, people would move with the animals so it prevented overgrazing in such areas. Now, humans have a steady food supply so they do not have to move about. Therefore, people use fences to keep their animals in one place which causes overgrazing.

Example-The Sahel Desert Around the 1950’s, people settled into the Sahel region, in areas where there was water. Overgrazing rate increased overtime resulting in the destruction of perennial shrubs and replaced with annuals. Annual shrubs were also overgrazed leaving bare soil vulnerable to degradation.

Example-The Sahel Desert top soil was washed away exposing the bed rocks and thus plants were not able to grow because their roots could not penetrate hard clay layers.

Human causes of desertification Farming of Average Land: is causing desertification worldwide. Farmers are clearing average land, and using it reducing the fertility and richness of the soil. People should let the average land replenish itself before farming. Destruction of Plants in Dry Regions: is causing desertification via cutting down tress to use as a source of fuel. Trees has a major role in soil protection and cutting them down would dry the bare soil and get blown away by wind.

Human causes of desertification Incorrect irrigation in arid regions: causes a build up of salt on the soil surface. This irrigation method is commonly used in poor areas in which farmers uses canal irrigation and other poor techniques because of water shortage.

The Effects Of Desertification Soil becomes less usable and easily be lost via erosion, nutrients in the soil can be removed by wind or water, salt can build up in the soil which makes it harder for plant growth. Vegetation is Lacked or Damaged due to soil loss and overgrazing. Famine: Places that have war and poverty are most likely to have famine. Drought and poor land management contribute to famine spreading.

The Effects Of Desertification Food Loss: soil is not suited for growing food; therefore the amount of food being made will decline. If the population is growing, this will cause economic problems and starvation. People near Affected Areas: Desertification can cause flooding, poor water quality, dust storms, and pollution. All of these effects can harm people living near an affected region.